Sample interview questions: Can you explain the process of test equating and how it helps ensure score comparability across different test forms?
Sample answer:
Test equating is a crucial process used in psychometrics to ensure score comparability across different test forms. It involves developing statistical methods to adjust test scores so that they can be meaningfully compared and interpreted across different versions of a test or across different testing occasions. The aim of test equating is to account for any variability in difficulty levels between test forms, ensuring that scores obtained on different forms are comparable and reflect the same underlying construct being measured.
The process of test equating typically involves three main steps: test administration, data collection, and statistical analysis. During the test administration phase, multiple test forms are administered to different groups of test takers. These forms are carefully designed to be parallel in terms of content coverage and difficulty level, but slight variations in difficulty may still occur due to differences in item characteristics or test administration conditions.
After the test administration, data collection takes place. Test takers’ responses on each test form are collected, along with relevant demographic information. This data serves as the basis for subsequent statistical analysis.
The statistical analysis phase involves using sophisticated equating methods to adjust test scores for any differences in difficulty levels between test forms. These methods rely on item response theory (IRT) models or classical test theory (CTT) methods to estimate the difficulty parameters of each item on the test forms. Equating methods such as the item response theory equating, test characteristic curve equating, or the equipercentile equating method are commonly employed.
Once the difficulty parameters are estimated, equating functions are created to transform raw scores from one test form to another, ensuring that scores obtained on different test forms are comparable. These equating functions are … Read full answer